I. Field of the Invention
This invention relates to a seal for connected sections of a vehicle exhaust system and, in particular, to a seal for the articulating ball joint of an exhaust system to eliminate leakage of exhaust.
II. Description of the Prior Art
In order to compensate for vibrations of the vehicle and thermal expansion, vehicle exhaust systems are typically constructed and mounted in segments. This also reduces costs in the event a section of the exhaust system requires replacement. The joints between segments are clamped together to allow for varying rates of thermal expansion and the vibrations of the vehicle. Typically, a section of exhaust pipe is matingly received within a the joint. In the past, exhaust leakage at such joints was not a concern since it was believed to be minimal and substantially ended up in the atmosphere along with the majority of the exhaust gases which travelled through the exhaust system.
With the advent and improvement of emission control systems, it has become advantageous to direct as much of the exhaust gases as possible through such emission devices. Additionally, federally mandated vehicle emission standards will require the elimination of exhaust leakage from the gas exit at the head port of the engine to aft of the catalytic converter or other emission control device. Such mandates causes the need for low pressure seal systems built of materials capable of withstanding high temperatures (950.degree. C.), are resistant to corrosives such as sulfuric acid and road salt, and are durable. Prior attempts at sealing the joints of an exhaust system have not met such stringent standards.